Raf Vervoort,^1,2,* Lucie E. Schmaltz,¹ Jos C.E.W. Hooijmeijer,¹ Yvonne I. Verkuil,¹ Bart Kempenaers,² Theunis Piersma<sup>1,3

1</sup>Rudi Drent Chair in Global Flyway Ecology, Conservation Ecology Group, Groningen Institute for Evolutionary Life Sciences (GELIFES), University of Groningen, P.O. Box 11103, 9700 CC Groningen, The Netherlands
²Department Behavioural Ecology & Evolutionary Genetics, Max Planck Institute for Ornithology, Eberhard-Gwinner-Strasse, 82319 Seewiesen, Germany
³NIOZ Royal Netherlands Institute for Sea Research, Department of Coastal Systems, P.O. Box 59, 1790 AB Den Burg, Texel, The Netherlands

^*corresponding author (ribvervoort@hotmail.com)